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�Engineers consume created a tiny motorised positioning device that has twice the dexterity of similar devices being highly-developed for applications that include biological sensors and more compact, knock-down computer hard drives.

The device, called a monolithic comb drive, mightiness be exploited as a "nanoscale manipulator" that exactly moves or senses movement and forces. The devices also throne be secondhand in watery environments for probing biologic molecules, aforesaid Jason Vaughn Clark, an assistant prof of electrical and figurer engineering and mechanical technology, who created the design.

The monolithic comb drives could make it possible to improve a class of probe-based sensors that discover viruses and biological molecules. The sensors detect objects using 2 different components: A probe is touched while at the same time the platform retention the specimen is positioned. The new technology would replace both components with a single one - the monolithic comb drive.

The innovation could allow sensors to work faster and at higher resolution and would be small sufficiency to fit on a microchip. The higher solution might be used to design next computer surd drives open of high-density data depot and retrieval. Another possible use mightiness be to fabricate or assemble miniature micro and nanoscale machines.

Research findings were detailed in a technical paper presented in July during the University Government Industry Micro/Nano Symposium in Louisville. The work is based at the Birck Nanotechnology Center at Purdue's Discovery Park.

Conventional comb drives have a pair of comblike sections with "interdigitated fingers," import they meshing together. These meshing fingers are haggard toward each other when a electric potential is applied. The applied voltage causes the fingers on unitary comb to become positively charged and the fingers on the other comb to become negatively aerated, inducing an attraction betwixt the oppositely charged fingers. If the voltage is removed, the spring-loaded comb sections return to their original position.

By comparison, the new monumental device has a single structure with two perpendicular style comb drives.

Clark calls the device monolithic because it contains comb drive components that ar not mechanically and electrically separate. Conventional comb drives are structurally "decoupled" to keep opposite charges separated.

"Comb drives represent an vantage over other technologies," Clark said. "In contrast to piezoelectric actuators that typically deflect, or move, a fraction of a micrometer, comb drives can turn away tens to hundreds of micrometers. And unlike conventional comb drives, which but move in one direction, our new device toilet move in two directions - left to right, forward and backward - an upgrade that could really subject up the door for many applications."

Clark also has invented a way to determine the precise warp and forcefulness of such microdevices while reducing heat-induced vibrations that could step in with measurements.

Current probe-based biologic sensors have a resolution of roughly 20 nanometers.

"Twenty nanometers is about the size of 200 atoms, so if you are scanning for a finical molecule, it may be hard to find," Clark said. "With our pattern, the higher atomic-scale resolution should make it easier to find."

Properly using such devices requires engineers to know precisely how often force is being applied to comb drive sensors and how far they are moving. The new design is based on a engineering science created by Clark called electro micro metrology, which enables engineers to determine the precise displacement and force that's being applied to, or by, a comb get. The Purdue researcher is able to measure this force by comparing changes in electrical properties such as capacitor or voltage.

Clark used computational methods called nodal analysis and finite element analysis to figure, model and simulate the monolithic comb drives.

The research paper describes how the monolithic comb drive plant when electromotive force is applied. The results show independent left-right and forward-backward bm as functions of applied voltage in color-coded graphics.

The findings are an extension of research to create an ultra-precise measuring system for devices having features on the size scale of nanometers, or billionths of a meter. Clark has light-emitting diode research to create devices that "self-calibrate," meaning they are able to on the dot measure themselves. Such measuring methods and standards are needed to better interpret and tap nanometer-scale devices.

The size of the integral device is less than one millimeter, or a thousandth of a time. The smallest feature size is about three micrometers, roughly one-thirtieth as broad as a human hair.

"You can make them littler, though," Clark said. "This is a proof of concept. The technology I'm developing should allow researchers to practically and expeditiously extract oodles of geometrical and material properties of their microdevices just by electronically probing changes in capacitance or voltage."

In gain to finite element analytic thinking, Clark used a simulation tool that he highly-developed called Sugar.

"Sugar is fast and allows me to easily try out many design ideas," he aforesaid. "After I narrow down to a particular pattern, I then use finite element psychoanalysis for fine-tuning. Finite element analysis is slow, merely it is able to model insidious physical phenomena that Sugar doesn't do as well."

Clark's research team is installing Sugar on the nanoHub this summer, making the tool available to other researchers. The nanoHub is operated by the Network for Computational Nanotechnology, funded by the National Science Foundation and housed at Purdue's Birck Nanotechnology Center.

The researchers as well are in the process of fabricating the devices at the Birck Nanotechnology Center.

Source: Emil Venere

Purdue University

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